Gl.LogicOp (gb.opengl)
Static Sub LogicOp ( Opcode As Integer )
Specify a logical pixel operation for rendering.
Parameters
- opcode
-
Specifies a symbolic constant that selects a logical operation.
The following symbols are accepted:
Gl.CLEAR_,
Gl.SET,
Gl.COPY,
Gl.COPY_INVERTED,
Gl.NOOP,
Gl.INVERT,
Gl.AND,
Gl.NAND,
Gl.OR,
Gl.NOR,
Gl.XOR,
Gl.EQUIV,
Gl.AND_REVERSE,
Gl.AND_INVERTED,
Gl.OR_REVERSE, and
Gl.OR_INVERTED. The initial value is Gl.COPY.
Description
Gl.LogicOp specifies a logical operation that,
when enabled,
is applied between the incoming RGBA color
and the RGBA color at the corresponding location in the
frame buffer.
To enable or disable the logical operation, call
Gl.Enable and Gl.Disable
using the symbolic constant
Gl.COLOR_LOGIC_OP. The initial value is
disabled.
opcode is a symbolic constant chosen from the list above.
In the explanation of the logical operations,
s represents the incoming color and
d represents the color in the frame buffer.
Standard C-language operators are used.
As these bitwise operators suggest,
the logical operation is applied independently to each bit pair of the
source and destination colors.
Notes
When more than one RGBA color buffer is enabled for drawing,
logical operations are performed separately for each enabled buffer,
using for the destination value the contents of that buffer
(see
Gl.DrawBuffer).
Logic operations have no effect on floating point draw buffers. However, if
Gl.COLOR_LOGIC_OP is enabled, blending is still disabled
in this case.
Errors
Gl.INVALID_ENUM is generated if
opcode is not an accepted value.
Associated Gets
Gl.Get with argument Gl.LOGIC_OP_MODE.
Gl.IsEnabled with argument
Gl.COLOR_LOGIC_OP.
See also
See original documentation on OpenGL website